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MEANS FOB. PREVENTING FALSE SIG'NALS UPON RBVERSAL S IN QUADRUPLEX TELEGRAPHS. 110,313,787. Patented Mar. 10, 1885.

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HENRY VAN HOEVENBERGH, OF ELIZABETH, NElV JERSEY.

MEANS FOR PREVENTINGFALSE SIGNALS UPON REVERSALS IN QUADRUPLEX TELEGRAPHS.

IBPECIPICATION forming part of Letters Patent No. 313,787, dated March 10, 1885.

(No model.)

To all whom, it may concern Be it known that l, HENRY VAN Honvan- BERGI-I, a citizen of the United States, residing in Elizabeth, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Quadruplex Telegraphy, of which the following is a speci' fication.

My invention relates to a system of telegraphy in which two independent signals or sets of signals may be simultaneously transmitted in the same direction over a single electric conductor. The different characteristics of the electrical impulses transmitted over the main conductor,in respect to their polarity and their strcngtln are interpret-ed at the receivingstation by suitable instruments through the agency of a system of local circuits and local batteries, which are socombined and arranged as to avoid thefalse signals which are produced upon the ordinary receiving instruments when the polarity of the current is reversed during the transmission of a signal.

The accompanying drawing,- which illustrates my invention, is a diagram showing the arrangement of circuits and instruments according to my improved system, A representing the transmitting apparatus at one end of the line, and B the receiving apparatus at the other end of the line.

Referring first to the transmitting apparatus, O is the main battery, divided into two unequal portions, O and 0 The portion 0' consists of, say, twice as many elements as the portion 0. T is an ordinary transmitter, the signals of which are interpreted at the receiving-station by the neutral relay, as hereinafter explained. This transmitter is preferably worked by means of the finger-key T, local circuit 15, and electromagnet t. K is a pole changing and circuit-preserving transmitter, the signals of which are interpreted by the polarized relay at the receiving-station, as hereinafter explained. This transmitter is preferably worked by the fingerlmy K, local circuit 7c, and electro-magnet k.

The above-described apparatus is of the ordinary and well-known construction and arrangement, and forms no part of my invention.

Referring to the receiving apparatus, P is a receiving-magnet provided with a polarized vibrating armature, p, pivoted at its lower end,

f, and moving to and fro at its upper end be tween the contact-stopsp and 11 His an ordinary neutral relay. Its armature m is pivoted at its lower end, m and it vibrates at its upper end between the contact stops m and in. These two receiving-magnets P and M are connected in series in the main line.

0 and 0 are local batteries connected with the armatures of the two receiving-magnets, and with the two receiving-instruments or sounders S and S.

R is an artificial resistance equal or approximately equal to the resistance of the electromagnet of the sounder S.

The main line may be traced from the earth at G at the transmitting-station through the main battery 0, the polc'changer K, the line L, the receiving neutral relay M, and polarized relay P, and to the ground at G. The operation of the system is as follows: WVhen the line is at rest and both keys are in their normal position, as shown in the drawing, the whole of the main battery 0 is to line, and the circuit passes from the positive end of the battery through the wire 1 to the transmitter T, thence through the wire 2 to the pole-changing transmitter K, thence through the main line L to the neutral relay M at the-receivingstation, thence by the wire 3 to the polarized relay P, and thence by wire 4: to the ground at G. From the other end of the battery the circuit leads through the wire 5 to the stop 0 of the circuitcontroller K, and by the wire 6 to the ground at G.

Vhen the transmitter T is depressed, which is done by depressing the key T, thus closing the local circuit 1, through the magnet t, the contact-spring t is brought against the contact-stop t", and the circuit is then formed through the lesser portion 0 only of the main battery, the connections being from the posi tive pole at the point O"'through the wire 7 to the contact-stop t, spring t wire 2, stop 0 of the pole-changer K, and line L to the receiving-instruments M and. P, and to the ground at G, while the connections from the other pole of the battery 0" remain as before. It is evident, therefore, that the operation of the transmitterTis to send the current alternately from the whole of the battery 0, and the smaller portion thereof, 0", into the main line.

Referring now to the neutral relay M at the receiving-station,the armature of this relay is normally held away from its poles by the retracting-spring s. The tension given to this spring is sufficient to draw .the armature m 7 s, and holds the armature to its poles, or

against the stop m". in the strength of the current, therefore, which passes over the line by the operation of the transmitter T, are interpreted by the magnet M, its armature m being drawn against the contact-stop m when the transmitter T is depressed, and is drawn by the magnet against the stop an when the transmitter T is raised. The polarized relay responds in a manner well understood to the changes in the polarity of the current passing through its coils without reference to its strength. Vhen, therefore, the pole-changing transmitter K is operated by means of the key K, local circuit 75, and magnet 70, thereby producing alternate reversals in the polarity of the current to line,

the armature p ofthe polarized receivingmagnet P plays to and fro in acorresponding manner between the stops p and p When the pole-changing transmitter K is at rest,the positive pole of the battery (whether of the whole battery or of the portion 0 only) is to line, as has already been explained, and the polarity of the magnet P is so arranged that its armature p, under these conditions, is carried to the left side, and is held against the stop 19. When the reversing-transmitter K is depressed,the battery 0 has its poles interchanged with respect to the line and earth, and the negative pole of the battery (whether of the whole battery or of the portion O only) is put to line, thus reversing the current therefrom. The armature p of the magnet P is then carried to the right and rests against the contact-stop p".

The selective action of thelocal circuits upon the class of signals transmitted over the main line to the receivers will now be explained.

The local batteries '0 and 0 are connected in a single local circuit, or in separate local circuits, according to the positions of the arma tures of the two relay-magnets. In order to explain their operation, let us suppose the apparatus to be at rest, as shown in the drawing. The entire main battery 0 being to line by its positive pole, the neutral relay M holds its armature m against the stop m. The polarized relayP holds its armature p to the left against the contact-stop 19 It is obvious that under these conditions neither the sounder S nor the sounder S will be operative. In regard to the sounder S, its circuit may be traced from the positive pole of the battery othrough the wire 8 to the armature p and contact-stop p resistance R, wire 9, to the negative pole of the local battery. The

The alternate changes sounder S is therefore, in fact, in an open sh untcircuit. In regard to the sounder S, the battery 0* may be traced from the positive pole through the Wire 10 to the armature 19, contactstop f, resistance R, wire 11, to the sounder S, contact-stop m. At this point the circuit is open, as the armatn rem is held against the back contact-stop, m". If now the transmitter T is depressed, the larger battery-section O is cut out of the circuit and the smaller section 0* only is sent to line. The result upon the "receiving-instruments is to release the armature m, which is drawn by the spring 8 against the contact-stop m It will readily be understood that the sounder S will now operate, for its circuit may be traced, in the same manner as before, from the positive pole of the local battery first around to the magnet and the contact-stop m thence through the armature and wire 12 to the negative pole of the same battery. It is evident, also, that the polarized relay P will not be affected by this action, for the main battery, though reduced in strength, remains with the same pole to line. When the transmitter T is released, the spring 8, attached thereto, instantly restores the whole of the main battery to line, the receiving-magnet M recalls its -armature, and the circuit of the sounder S is again broken. Thus it will be seen that thesignals of the telegraphic code maybe produced upon the sounder S by the operation of the transmitter T.

Referring now to the pole-changing key K and the means for transmitting signals thereby, as has been explained, the armature p of the relay P rests against the left contact-stop, 12 when the line is in the condition shown in the drawing-that is, with the positive pole of the battery to the line. WVhen the lever K is depressed by means of the key K, local circuit k, and magnet the main battery is reversed, the negative pole goes to line,the armature 10 moves to the right and rests against the contact-stop p". This actuates the sounder S, for its circuit may be traced from the battery 0, as before, by wire 8, armature 10, contactstop f, sounder, and Wire 9 to the battery. WVhen the lever K is released, its spring 8 restores the former condition of at'fairsthat is to say, the battery is changed back, so that the positive pole goes to line, the armaturep returns to its left stop, f, and the circuit of the sounder S is open. Thus it will be seen that telegraph-signals will be produced upon the sounder S by operating the lever K of the pole'changing key.

It is evident that the operation of the two transmitters T and K in no wise interfere with each other, but that each will independently produce its signals upon its proper sounder at the receiving-station.

It will now be shown howfalse signalsupon the relay M and sounder S are avoided by this system. These false signals, as is well known, tend to be produced upon the neutral relay at the instant of reversal of the entire main bat- ICC tery. When the pole-changer K is operated with the full strength of the battery upon the line, it is evident that there will be an instant at each reversal when there is no current upon the line. At this instant the spring 8 of the neutral relay M will begin to draw the armature-lever m toward the stop m The polarized armature p of the relay 1? will remain against one of the stops or 19 for it will not move until the reversed current begins to act. Before the armature-lever in, however, has reached the stop at the armature will have left its stop, and will be on its way between its two contact-stops. When in this position, no

75 false signal can be given upon the sounder'S for the following reason: The local batteries 0 and 0 have-their positive poles opposed to each other. The battery 0 consists of two elements in series, the battery 0 consists of one ele ment only-that is, the batteryo has twice the electro-motive force of the battery 0. The sounder S is adapted to respond to the current of the battery 0 of one element. The sounder S is adjusted to respond only to the full ourrent of the battery 0 of two elements. \Vhen the armature pisin the middle position, there fore, the current from the battery 0, passing through the wires 10 and S to the battery 0,

is reduced to half its strength by the opposing 3o electro-motive force of the latter, and passing by the wires 9 and 11 to the magnet, and then to the outer pole of the battery 0, is insufficient to work the sounder S. At theinstant of reversal therefore,when the impulses 3 5 ordinarily causing false signals arise, the local circuits are in such condition thatthe false signals cannot in any manner affect the sounders.

hen bot-h transmitting-keys T and K are depressed at the same time, each of the receivingmagnets responds to its own signal indeo pendently. Thus the armature p is drawn to the right of the contact stop 19 though of course only with the force due to the action of the battery-section o,while the armature m of the relaymagnet M, being attracted by the 5 magnet with only the force due to the batterysection 0, is drawn by the springsagainstthe contact-stop m and its signal is recorded by the sounder S. a

Any ordinary or well-known system of dupleX telegraphy in opposite directions may be applied to or combined with the apparatus which has been described in order to constitute a quadruplex system.

I claim as my invention- In a quadruplex telegraph,the hereinbeforedescribed method of preventing false signals upon the receiving-instrument controlled by the armature of the neutral relay upon the reversal of the main-line current,which consists in momentarily neutralizing the local current actuating said receiving-instrument by means of an opposing electro-motive force.

In testimony whereof I have hereunto subscribed my name this l7rth day of November, A. D. 1884.

HENRY VAN HOEVENBERGH.

Witnesses:

DANL. WV. EDGECOMB, CHARLES A. TERRY. 

